When tracks are laid in the conventional way on a ballast track, rainwater seeps through the track ballast and is led along a subgrade protective layer towards the exterior. Thus, rainwater is largely prevented from accumulating near the tracks. However, tracks resting on a ballast track are disadvantageous for high-speed railroad traffic, and therefore a fixed rail track is installed most of the time. In the fixed track, a hydraulically-bound supporting layer is built directly on the subgrade protective layer, after which the fixed track is laid on the supporting layer. The former is made of concrete mixed in situ or of pre-assembled slabs. In the case of the fixed tracks made of concrete mixed in situ, pre-fabricated ties or rail supports are often laid exactly on position and finally poured with concrete mixed in situ. If the fixed track is made from pre-assembled concrete, then they already come with rail supports. The pre-assembled concrete slabs are finally laid on the hydraulically-bound supporting layer and fastened.
In both types of fabrication, the fixed track is built with a superelevation in the area of transition curves and radii. In other words, the delivered slab for the fixed track made of pre-fabricated concrete or concrete mixed in situ is built in a sloping way on the respective supporting layer prepared for it. In a track system, which is usually made of at least two tracks largely parallel to one another, rainwater falling on the track located in the interior of the curve flows to the internal outer side of the track system, but rainwater falling on the outer track, on the other hand, will flow between both tracks. The water in this middle area must be forced to flow out with a drainage device installed under the fixed track.
From the engineering standpoint, it is not too difficult to build a new fixed track. However, if a track system must be rebuilt from a ballast track to a fixed track, it can get difficult, since most of the time rail traffic cannot be interrupted and larger rebuilding measures cannot therefore be taken.